RESUMO
The fungal metabolite sphaeropsidin A (SphA) has been recognised for its promising cytotoxicity, particularly towards apoptosis- and multidrug-resistant cancers. Owing to its intriguing activity, the development of SphA as a potential anticancer agent has been pursued. However, this endeavour is compromised since SphA exhibits poor physicochemical stability under physiological conditions. Herein, SphA's instability in biological media was explored utilizing LC-MS. Notably, the degradation tendency was found to be markedly enhanced in the presence of amino acids in the cell medium utilized. Furthermore, the study investigated the presence of degradation adducts, including the identification, isolation and structural elucidation of a major degradation metabolite, (4R)-4,4',4'-trimethyl-3'-oxo-4-vinyl-4',5',6',7'-tetrahydro-3'H-spiro[cyclohexane-1,1'-isobenzofuran]-2-ene-2-carboxylic acid. Considering the reduced cytotoxic potency of aged SphA solutions, as well as that of the isolated degradation metabolite, the reported antiproliferative activity has been attributed primarily to the parent compound (SphA) and not its degradation species. The fact that SphA continues to exhibit remarkable bioactivity, despite being susceptible to degradation, motivates future research efforts to address the challenges associated with this instability impediment.
Assuntos
DiterpenosRESUMO
The O-glucuronide of vildagliptin, a dipeptidyl peptidase 4 inhibitor, is a major metabolite in monkeys and a minor metabolite in humans, rats, and dogs. Its product ion spectrum shows fragments that can be explained only by an N-glucuronide. Biotransformation using rat liver yielded milligram amounts of the O-glucuronide, and its structure was assigned unambiguously by nuclear magnetic resonance. The tandem mass spectra (MS/MS) of this compound was investigated in detail using MSn and accurate mass spectrometers and was identical to the animal metabolite. Thus, the MS/MS fragments suggesting an N-glucuronide had to be formed by gas-phase rearrangement. This gas-phase rearrangement can be observed on quadrupole time-of-flight and ion-trap mass instruments. The literature on gas-phase rearrangements is reviewed.
Assuntos
Inibidores da Dipeptidil Peptidase IV/química , Glucuronídeos/química , Transição de Fase , Vildagliptina/química , Inibidores da Dipeptidil Peptidase IV/análise , Inibidores da Dipeptidil Peptidase IV/metabolismo , Glucuronídeos/análise , Glucuronídeos/metabolismo , Íons , Espectroscopia de Ressonância Magnética , Estrutura Molecular , Espectrometria de Massas por Ionização por Electrospray , Espectrometria de Massas em Tandem , Vildagliptina/análise , Vildagliptina/metabolismoRESUMO
A new cyclic decadepsipeptide was isolated from Chaetosphaeria tulasneorum with potent bioactivity on mammalian and yeast cells. Chemogenomic profiling in S. cerevisiae indicated that the Sec61 translocon complex, the machinery for protein translocation and membrane insertion at the endoplasmic reticulum, is the target. The profiles were similar to those of cyclic heptadepsipeptides of a distinct chemotype (including HUN-7293 and cotransin) that had previously been shown to inhibit cotranslational translocation at the mammalian Sec61 translocon. Unbiased, genome-wide mutagenesis followed by full-genome sequencing in both fungal and mammalian cells identified dominant mutations in Sec61p (yeast) or Sec61α1 (mammals) that conferred resistance. Most, but not all, of these mutations affected inhibition by both chemotypes, despite an absence of structural similarity. Biochemical analysis confirmed inhibition of protein translocation into the endoplasmic reticulum of both co- and post-translationally translocated substrates by both chemotypes, demonstrating a mechanism independent of a translating ribosome. Most interestingly, both chemotypes were found to also inhibit SecYEG, the bacterial Sec61 translocon homolog. We suggest 'decatransin' as the name for this new decadepsipeptide translocation inhibitor.
Assuntos
Produtos Biológicos/farmacologia , Retículo Endoplasmático/efeitos dos fármacos , Proteínas de Membrana/metabolismo , Transporte Proteico/efeitos dos fármacos , Proteínas de Saccharomyces cerevisiae/metabolismo , Saccharomyces cerevisiae/metabolismo , Animais , Ascomicetos/metabolismo , Células COS , Células Cultivadas , Chlorocebus aethiops , Células HCT116 , Humanos , Proteínas de Membrana/antagonistas & inibidores , Peptídeos Cíclicos/farmacologia , Polimorfismo de Nucleotídeo Único/genética , Canais de Translocação SEC , Saccharomyces cerevisiae/genética , Saccharomyces cerevisiae/crescimento & desenvolvimentoRESUMO
Two new unusual dimeric selaginellins, diselaginellins A and B (1 and 2), along with two known derivatives, selaginellin (3) and selaginellin B (4), were isolated from Selaginella pulvinata. Their structures were elucidated by extensive NMR and high-resolution ESIMS data analysis. Compound 2 displayed apoptosis-inducing and antimetastatic activities against the human hepatocellular carcinoma cell line SMMC-7721. A microarray analysis revealed that genes related to metabolism, angiogenesis, and metastasis were altered by 2. The up- and down-regulation of the mRNA levels of related genes was confirmed by RT-qPCR. Metabolism modulation and metastasis inhibition might be the mechanisms of the antitumor properties of diselaginellin B (2).
Assuntos
Compostos de Bifenilo/química , Compostos de Bifenilo/farmacologia , Carcinoma Hepatocelular/tratamento farmacológico , Cicloexanonas/química , Cicloexanonas/farmacologia , Neoplasias Hepáticas/tratamento farmacológico , Selaginellaceae/química , Antineoplásicos Fitogênicos/química , Antineoplásicos Fitogênicos/farmacologia , Apoptose/efeitos dos fármacos , Carcinoma Hepatocelular/patologia , Linhagem Celular Tumoral , Regulação para Baixo/efeitos dos fármacos , Humanos , Neoplasias Hepáticas/patologia , Espectroscopia de Ressonância Magnética/métodos , Metástase Neoplásica , Extratos Vegetais/química , Extratos Vegetais/farmacologia , Regulação para Cima/efeitos dos fármacosRESUMO
One new flavonoid glycoside, along with three known flavonoid glycosides were isolated from the stem bark of Margaritaria discoidea, which is traditionally used in the management of wounds and skin infections in Ghana. The new flavonoid glycoside was elucidated as hydroxygenkwanin-8-C-[α-rhamnopyranosyl-(1 â 6)]-ß-glucopyranoside (1) on the basis of spectroscopic analysis. The isolated compounds demonstrated free-radical scavenging as well as some level of antibacterial activities. Microorganisms including Staphylococcus aureus are implicated in inhibiting or delaying wound healing. Therefore, any agent capable of reducing or eliminating the microbial load present in a wound as well as decreasing the levels of reactive oxygen species may facilitate the healing process. These findings therefore provide some support to the ethnopharmacological usage of the plant in the management of wounds.
Assuntos
Antibacterianos/farmacologia , Flavonoides/farmacologia , Sequestradores de Radicais Livres/farmacologia , Glicosídeos/farmacologia , Magnoliopsida/química , Extratos Vegetais/química , Antibacterianos/química , Antibacterianos/isolamento & purificação , Flavonoides/química , Flavonoides/isolamento & purificação , Sequestradores de Radicais Livres/química , Sequestradores de Radicais Livres/isolamento & purificação , Glicosídeos/química , Glicosídeos/isolamento & purificação , Casca de Planta/químicaRESUMO
This study investigated the antibacterial, resistance modulation, biofilm inhibition, and efflux pump inhibition potentials of Loeseneriella africana stem extract and its constituents. The antimicrobial activity was investigated by the high-throughput spot culture growth inhibition (HT-SPOTi) and broth microdilution assays. The resistance modulation activity was investigated using the anti-biofilm formation and efflux pump inhibition assays. Purification of the extract was carried out by chromatographic methods, and the isolated compounds were characterized based on nuclear magnetic resonance, Fourier transform infrared and mass spectrometry spectral data and comparison with published literature. The whole extract, methanol, ethyl acetate, and pet-ether fractions of L. africana all showed antibacterial activity against the test bacteria with MICs ranging from 62.5 to 500.0 µg/mL The whole extract demonstrated resistance modulation effect through strong biofilm inhibition and efflux pump inhibition activities against S. aureus ATCC 25923, E. coli ATCC 25922 and P. aeruginosa ATCC 27853. Chromatographic fractionation of the ethyl acetate fraction resulted in the isolation of a triterpenoid (4S,4αS,6αR,6ßS,8αS,12αS,12ßR,14αS,14ßR)-4,4α,6ß,8α,11,11,12ß,14α-Octamethyloctadecahydropicene-1,3(2H,4H)-dione) and a phytosterol (ß-sitosterol). These compounds showed antibacterial activity against susceptible bacteria at a MIC range of 31-125 µg/mL and potentiated the antibacterial activity of amoxicillin (at » MIC of compounds) against E. coli and P. aeruginosa with modulation factors of 32 and 10, respectively. These compounds also demonstrated good anti-biofilm formation effect at a concentration range of 3-100 µg/mL, and bacterial efflux pump inhibition activity at ½ MIC and » MIC against E. coli and P. aeruginosa. Loeseneriella africana stem bark extracts and constituents elicit considerable antibacterial, resistance modulation, and biofilm and efflux pump inhibition activities. The results justify the indigenous uses of L. africana for managing microbial infections.
RESUMO
Panobinostat (LBH589) is a novel pan-deacetylase inhibitor that is currently being evaluated in phase III clinical trials for treatment of Hodgkin's lymphoma and multiple myeloma. Under catalysis of recombinant human CYP3A4 and CYP2D6 coexpressed with human cytochrome P450 reductase in Escherichia coli JM109, five metabolites of panobinostat were produced via whole-cell biotransformation. The structures of the metabolites were elucidated with the spectroscopic methods mass spectrometry (MS) and NMR and revealed an oxidative cyclization of the ethyl-amino group to the methylindole moiety. The MS(2) spectrum of the cyclized metabolite showed a base peak, where the closed ring is reopened and that, taken as sole base for structure proposals, would have lead to wrong conclusions. The metabolites were substantially less potent deacetylase inhibitors than the parent compound.
Assuntos
Antineoplásicos , Citocromo P-450 CYP2D6/metabolismo , Citocromo P-450 CYP3A/metabolismo , Inibidores de Histona Desacetilases , Ácidos Hidroxâmicos , Antineoplásicos/química , Antineoplásicos/metabolismo , Antineoplásicos/farmacologia , Biocatálise , Biotransformação , Cromatografia Líquida de Alta Pressão , Ciclização , Citocromo P-450 CYP2D6/genética , Citocromo P-450 CYP3A/genética , Escherichia coli/genética , Inibidores de Histona Desacetilases/química , Inibidores de Histona Desacetilases/metabolismo , Inibidores de Histona Desacetilases/farmacologia , Humanos , Ácidos Hidroxâmicos/química , Ácidos Hidroxâmicos/metabolismo , Ácidos Hidroxâmicos/farmacologia , Indóis , Conformação Molecular , Panobinostat , Espectrometria de Massas em TandemRESUMO
Ligand-based 19 F NMR screening is a highly effective and well-established hit-finding approach. The high sensitivity to protein binding makes it particularly suitable for fragment screening. Different criteria can be considered for generating fluorinated fragment libraries. One common strategy is to assemble a large, diverse, well-designed and characterized fragment library which is screened in mixtures, generated based on experimental 19 F NMR chemical shifts. Here, we introduce a complementary knowledge-based 19 F NMR screening approach, named 19 Focused screening, enabling the efficient screening of putative active molecules selected by computational hit finding methodologies, in mixtures assembled and on-the-fly deconvoluted based on predicted 19 F NMR chemical shifts. In this study, we developed a novel approach, named LEFshift, for 19 F NMR chemical shift prediction using rooted topological fluorine torsion fingerprints in combination with a random forest machine learning method. A demonstration of this approach to a real test case is reported.
Assuntos
Flúor , Imageamento por Ressonância Magnética , Flúor/química , Ligantes , Espectroscopia de Ressonância Magnética/métodos , Ligação ProteicaRESUMO
Six selaginellin derivatives, including three new analogues selaginellins D-F (1-3), were isolated from the EtOAc extract of the whole plant of Selaginella pulvinata (Hook. et Grev.) Maxim. Their structures were determined on the basis of extensive physical and chemical evidence. Compounds 1 and 4 demonstrated antifungal activities against Candida albicans; compounds 4-6 exhibited significant antibacterial activity against Staphylococcus aureus.
Assuntos
Anti-Infecciosos/isolamento & purificação , Compostos Benzidrílicos/isolamento & purificação , Cicloexanonas/isolamento & purificação , Extratos Vegetais/farmacologia , Selaginellaceae/química , Anti-Infecciosos/química , Anti-Infecciosos/farmacologia , Compostos Benzidrílicos/química , Compostos Benzidrílicos/farmacologia , Candida albicans/efeitos dos fármacos , Cicloexanonas/química , Cicloexanonas/farmacologia , Espectroscopia de Ressonância Magnética , Testes de Sensibilidade Microbiana , Modelos Moleculares , Staphylococcus aureus/efeitos dos fármacosRESUMO
We identified the thiomuracins, a novel family of thiopeptides produced by a rare-actinomycete bacterium typed as a Nonomuraea species, via a screen for inhibition of growth of the bacterial pathogen Staphylococcus aureus. Thiopeptides are a class of macrocyclic, highly modified peptides that are decorated by thiazoles and defined by a central six-membered heterocyclic ring system. Mining the genomes of thiopeptide-producing strains revealed the elusive biosynthetic route for this class of antibiotics. The thiopeptides are chromosomally encoded, ribosomally synthesized proteins, and isolation of gene clusters for production of thiomuracin and the related thiopeptide GE2270A revealed the post-translational machinery required for maturation. The target of the thiomuracins was identified as bacterial Elongation Factor Tu (EF-Tu). In addition to potently inhibiting a target that is unexploited by marketed human therapeutics, the thiomuracins have a low propensity for selecting for antibiotic resistance and confer no measurable cross-resistance to antibiotics in clinical use.
Assuntos
Antibacterianos/farmacologia , Fator Tu de Elongação de Peptídeos/metabolismo , Peptídeos/genética , Peptídeos/farmacologia , Staphylococcus aureus/efeitos dos fármacos , Tiazóis/farmacologia , Actinomycetales/química , Sequência de Aminoácidos , Antibacterianos/química , Antibacterianos/isolamento & purificação , Proteínas de Bactérias/isolamento & purificação , Proteínas de Bactérias/metabolismo , Proteínas de Bactérias/farmacologia , Regulação Bacteriana da Expressão Gênica , Genes Bacterianos , Dados de Sequência Molecular , Peptídeos/química , Peptídeos/isolamento & purificação , Biossíntese de Proteínas , Staphylococcus aureus/crescimento & desenvolvimento , Tiazóis/química , Tiazóis/isolamento & purificaçãoRESUMO
The special ergoline 1 is a highly potent, selective antagonist of the chemokine receptor CXCR3. The surprising selectivity of this LSD-related compound can be explained by different electronic and steric properties of the ergoline core structure caused by the urea portion of the molecule. Discovery, biopharmaceutical properties and first derivatives of this promising lead compound are discussed.
Assuntos
Ergolinas/química , Receptores CXCR3/antagonistas & inibidores , Animais , Cães , Descoberta de Drogas , Ergolinas/farmacologia , Humanos , Camundongos , Microssomos Hepáticos/metabolismo , Conformação Molecular , Ratos , Receptores CXCR3/metabolismo , Relação Estrutura-AtividadeRESUMO
FR171456 is a natural product with cholesterol-lowering properties in animal models, but its molecular target is unknown, which hinders further drug development. Here we show that FR171456 specifically targets the sterol-4-alpha-carboxylate-3-dehydrogenase (Saccharomyces cerevisiae--Erg26p, Homo sapiens--NSDHL (NAD(P) dependent steroid dehydrogenase-like)), an essential enzyme in the ergosterol/cholesterol biosynthesis pathway. FR171456 significantly alters the levels of cholesterol pathway intermediates in human and yeast cells. Genome-wide yeast haploinsufficiency profiling experiments highlight the erg26/ERG26 strain, and multiple mutations in ERG26 confer resistance to FR171456 in growth and enzyme assays. Some of these ERG26 mutations likely alter Erg26 binding to FR171456, based on a model of Erg26. Finally, we show that FR171456 inhibits an artificial Hepatitis C viral replicon, and has broad antifungal activity, suggesting potential additional utility as an anti-infective. The discovery of the target and binding site of FR171456 within the target will aid further development of this compound.
Assuntos
3-Hidroxiesteroide Desidrogenases/antagonistas & inibidores , Antifúngicos/química , Colesterol/análogos & derivados , Proteínas de Saccharomyces cerevisiae/antagonistas & inibidores , Saccharomyces cerevisiae/genética , 3-Hidroxiesteroide Desidrogenases/genética , Candida albicans , Colesterol/química , Farmacorresistência Fúngica/genética , Ergosterol/biossíntese , Mutação , Proteínas de Saccharomyces cerevisiae/genéticaRESUMO
The chemokine receptor CCR5 plays an important role in inflammatory and autoimmune disorders as well as in transplant rejection by affecting the trafficking of effector T cells and monocytes to diseased tissues. Antagonists of CCR5 are believed to be of potential therapeutic value for the disorders mentioned above and HIV infection. Here we report on the structure-activity relationship of a new series of highly potent and selective competitive CCR5 antagonists. While all compounds tested were inactive on rodent CCR5, this series includes compounds that cross-react with the cynomolgus monkey (cyno) receptor. One of these compounds, i.e., 26n, has good PK properties in cynos, and its overall favorable profile makes it a promising candidate for in vivo profiling in transplantation and other disease models.
Assuntos
Antagonistas dos Receptores CCR5 , Difenilamina/síntese química , Pirimidinonas/síntese química , Administração Oral , Animais , Disponibilidade Biológica , Cálcio/metabolismo , Linhagem Celular , Quimiotaxia de Leucócito , Cricetinae , Cristalografia por Raios X , Óxidos N-Cíclicos , Difenilamina/análogos & derivados , Difenilamina/química , Difenilamina/farmacologia , Humanos , Técnicas In Vitro , Linfócitos/efeitos dos fármacos , Linfócitos/fisiologia , Macaca fascicularis , Camundongos , Estrutura Molecular , Piperidinas , Pirimidinas , Pirimidinonas/química , Pirimidinonas/farmacologia , Ensaio Radioligante , Ratos , Relação Estrutura-AtividadeRESUMO
Two depsipeptide metabolites, scyptolin A and B, were reported recently from the axenically grown terrestrial cyanobacterium Scytonema hofmanni PCC 7110. A related, novel depsipeptide was isolated from this Scytonema and designated hofmannolin. The amino acid analysis in context with infrared, mass and 1H/13C-NMR spectroscopies revealed a cyclic depsipeptide structure of M(r) 1073 belonging to the class of cyanopeptolins. Two peculiar features distinguish hofmannolin from other cyanopeptolins: O-methylated tyrosine forms the sixth moiety from the amino terminus, and the N-terminus is blocked by 2-hydroxy-3-methyl-valeric acid, a residue that has not yet been reported as a component in other cyanopeptolins. Preliminary assays of peptidase inhibitory and antimicrobial activities suggested negligible bioactivities for hofmannolin.
Assuntos
Cianobactérias/química , Peptídeos Cíclicos/química , Peptídeos Cíclicos/isolamento & purificação , Sequência de Aminoácidos , Anti-Infecciosos/isolamento & purificação , Anti-Infecciosos/farmacologia , Candida albicans/efeitos dos fármacos , Cianobactérias/genética , Bactérias Gram-Negativas/efeitos dos fármacos , Bactérias Gram-Positivas/efeitos dos fármacos , Ressonância Magnética Nuclear Biomolecular , Peptídeos Cíclicos/farmacologia , Inibidores de Proteases/isolamento & purificação , Inibidores de Proteases/farmacologia , Conformação Proteica , Espectrometria de Massas por Ionização por Electrospray/métodos , Espectrometria de Massas por Ionização e Dessorção a Laser Assistida por Matriz/métodosRESUMO
Proansamycin B, the formerly postulated intermediate of rifamycin B biosynthesis, was isolated from cultures of the Amycolatopsis mediterranei mutant F1/24. The structure was determined using UV, IR, NMR and MS techniques. Biotransformation studies demonstrate that proansamycin B is an intermediate of a shunt pathway, a 8-deoxy variant, of rifamycin B biosynthesis leading to 8-deoxy-rifamycin B as the final product. In addition, 34a-deoxy-rifamycin W, the direct precursor of rifamycin W, could be isolated representing the earliest macrocyclic intermediate obtained so far in the biosynthetic route to rifamycin B. Furthermore, the new rifamycin W-28-desmethyl-28-carboxy and rifamycin W-hemiacetal, intermediates in the transformation sequence of rifamycin W to rifamycin S, were isolated. Application of proton NMR measurements (double resonance and ROESY experiments) on the latter compound indicated that the stereochemistry at the chiral center C-28 is R.
Assuntos
Actinomycetales/metabolismo , Antibacterianos/biossíntese , Rifamicinas/biossíntese , Rifamicinas/isolamento & purificação , Actinomycetales/genética , Actinomycetales/crescimento & desenvolvimento , Antibacterianos/química , Antibacterianos/isolamento & purificação , Cromatografia Líquida de Alta Pressão , Cromatografia em Camada Fina , Espectroscopia de Ressonância Magnética , Estrutura Molecular , Rifamicinas/química , Espectrofotometria UltravioletaRESUMO
The structures of argyrins A-H were elucidated by NMR spectroscopy, chemical degradation and X-ray analysis as cyclic octapeptides. Argyrins A and B, in addition to the common amino acids tryptophan, glycine, dehydroalanine and alanine or alpha-aminobutyric acid, sarcosine, contain 2-(1-aminoethyl)thiazol-4-caboxylic acid and the novel amino acid 4'-methoxytryptophan. In argyrins C and D the latter is replaced by 4'-methoxy 2'-methyltryptophan. According to NMR analysis the solution and crystal conformations of argyrins A and B are identical in CDCl3 and slightly different in acetone-d6. Argyrins A and B are identical with the antibiotics A21459 A and B, whose structures are revised with respect to 4'-methoxytryptophan.
Assuntos
Imunossupressores/química , Peptídeos Cíclicos/química , Cristalografia por Raios X , Espectroscopia de Ressonância Magnética , Conformação Molecular , Myxococcales/metabolismoRESUMO
A prodrug approach to optimize the oral exposure of a series of sphingosine 1-phosphate receptor 1 (S1P(1)) antagonists for chronic efficacy studies led to the discovery of (S)-2-{[3'-(4-chloro-2,5-dimethylphenylsulfonylamino)-3,5-dimethylbiphenyl-4-carbonyl]methylamino}-4-dimethylaminobutyric acid methyl ester 14. Methyl ester prodrug 14 is hydrolyzed in vivo to the corresponding carboxylic acid 15, a potent and selective S1P(1) antagonist. Oral administration of the prodrug 14 induces sustained peripheral blood lymphocyte reduction in rats. In a rat cardiac transplantation model coadministration of a nonefficacious dose of prodrug 14 with a nonefficacious dose of sotrastaurin (19), a protein kinase C inhibitor, or everolimus (20), an mTOR inhibitor, effectively prolonged the survival time of rat cardiac allografts. This demonstrates that clinically useful immunomodulation mediated by the S1P(1) receptor can be achieved with an S1P(1) antagonist generated in vivo after oral administration of its prodrug.
Assuntos
Aminobutiratos/síntese química , Transplante de Coração , Linfócitos/efeitos dos fármacos , Pró-Fármacos/síntese química , Receptores de Lisoesfingolipídeo/antagonistas & inibidores , Sulfonamidas/síntese química , Administração Oral , Aminobutiratos/administração & dosagem , Aminobutiratos/farmacologia , Animais , Linfócitos/metabolismo , Espectroscopia de Ressonância Magnética , Masculino , Estrutura Molecular , Pró-Fármacos/administração & dosagem , Pró-Fármacos/farmacologia , Ratos , Ratos Endogâmicos Lew , Sulfonamidas/administração & dosagem , Sulfonamidas/farmacologiaRESUMO
Aliskiren (2(S),4(S),5(S),7(S)-N-(2-carbamoyl-2-methylpropyl)-5-amino-4-hydroxy-2,7-diisopropyl-8-[4-methoxy-3-(3-methoxypropoxy)phenyl]-octanamid hemifumarate) is the first in a new class of orally active, nonpeptide direct renin inhibitors developed for the treatment of hypertension. The absorption, distribution, metabolism, and excretion of [(14)C]aliskiren were investigated in four healthy male subjects after administration of a single 300-mg oral dose in an aqueous solution. Plasma radioactivity and aliskiren concentration measurements and complete urine and feces collections were made for 168 h postdose. Peak plasma levels of aliskiren (C(max)) were achieved between 2 and 5 h postdose. Unchanged aliskiren represented the principal circulating species in plasma, accounting for 81% of total plasma radioactivity (AUC(0-infinity)), and indicating very low exposure to metabolites. Terminal half-lives for radioactivity and aliskiren in plasma were 49 h and 44 h, respectively. Dose recovery over 168 h was nearly complete (91.5% of dose); excretion occurred almost completely via the fecal route (90.9%), with only 0.6% recovered in the urine. Unabsorbed drug accounted for a large dose proportion recovered in feces in unchanged form. Based on results from this and from previous studies, the absorbed fraction of aliskiren can be estimated to approximately 5% of dose. The absorbed dose was partly eliminated unchanged via the hepatobiliary route. Oxidized metabolites in excreta accounted for at least 1.3% of the radioactive dose. The major metabolic pathways for aliskiren were O-demethylation at the phenyl-propoxy side chain or 3-methoxy-propoxy group, with further oxidation to the carboxylic acid derivative.
Assuntos
Amidas/metabolismo , Amidas/farmacocinética , Fumaratos/metabolismo , Fumaratos/farmacocinética , Renina/antagonistas & inibidores , Adulto , Amidas/sangue , Anti-Hipertensivos/metabolismo , Anti-Hipertensivos/farmacocinética , Anti-Hipertensivos/urina , Área Sob a Curva , Biotransformação , Fezes/química , Fumaratos/sangue , Humanos , Absorção Intestinal , Masculino , Pessoa de Meia-Idade , Estrutura Molecular , Espectrometria de Massas por Ionização por Electrospray , Distribuição Tecidual , Urina/químicaRESUMO
Careful regulation of mRNA half-lives is a fundamental mechanism allowing cells to quickly respond to changing environmental conditions. The mRNA-binding Hu proteins are important for stabilization of short-lived mRNAs. Here we describe the identification and mechanistic characterization of the first low-molecular-weight inhibitors for Hu protein R (HuR) from microbial broths (Actinomyces sp.): dehydromutactin (1), MS-444 (2) and okicenone (3). These compounds interfere with HuR RNA binding, HuR trafficking, cytokine expression and T-cell activation. A mathematical and experimental analysis of the compounds' mode of action suggests that HuR homodimerizes before RNA binding and that the compounds interfere with the formation of HuR dimers. Our results demonstrate the chemical drugability of HuR; to our knowledge HuR is the first example of a drugable protein within the Hu family. MS-444, dehydromutactin and okicenone may become valuable tools for studying HuR function. An assessment of HuR inhibition as a central node in malignant processes might open up new conceptual routes toward combatting cancer.
Assuntos
Antígenos de Superfície/química , Avaliação Pré-Clínica de Medicamentos/métodos , Proteínas de Ligação a RNA/química , Actinomyces/metabolismo , Antracenos/química , Anti-Infecciosos/química , Ligação Competitiva , Relação Dose-Resposta a Droga , Desenho de Fármacos , Proteínas ELAV , Proteína Semelhante a ELAV 1 , Polarização de Fluorescência , Furanos/química , Humanos , Cinética , Modelos Teóricos , Dados de Sequência Molecular , Naftóis/química , Pironas/químicaRESUMO
The absolute purities of 20 purified samples from a combinatorial library have been determined by a new method that uses the DMSO sidebands [1J[13C-1H]] as an internal standard for quantification. The obtained absolute amounts are compared with the amounts of sample obtained by weighing, with the calculated weights obtained by chemiluminescent nitrogen detection (CLND) chromatography and with the relative purities obtained by LC-UV chromatography.